File Upload (POC)

This adds a minimal, in-memory file upload capability wired to the chat composer and a Next.js API route.

What was added

• UI (src/components/Composer.tsx):
  • onUploadFile prop: (file: { id: string; file: File }) => Promise<unknown>
  • Hidden native file input + Attach button (design system) with paperclip icon
  • Upload state chips with statuses: Uploading → Uploaded
  • Cross button on each chip to remove files before sending
  • Send button disabled while any file is uploading
  • On submit, uploaded files are included in the message context and local upload state is cleared
• API:
  • POST /api/files (src/app/api/files/route.ts) accepts multipart/form-data with one or more file fields and optional id
  • Files are stored in-memory as text (using File.text())
  • In-memory store: src/app/api/files/fileStore.ts with addFile, removeFile, getFile, listFiles
  • POST /api/chat (src/app/api/chat/route.ts) includes read_file tool in the system prompt

API details

• Endpoint: POST /api/files
• Body: multipart/form-data
  • file: one or more file parts
  • id (optional): client-generated ID to correlate UI with server state
• Response: { files: Array<{ id, name, type, size }> }
• Storage: in-memory, text-only; not persisted, cleared on server restart

Caveats

• This approach is only suitable for text-based files like CSV, JSON, etc.
• In-memory store is not suitable for production (no persistence, no limits)
• Consider size limits, validation, and auth for real-world use